The present application pertains to devices for agitating a hopper portion of a material delivery apparatus and for sensing the volume condition of the material retained in the hopper portion.
A variety of beverage brewing apparatus have been developed in order to brew beverages with a minimum of human intervention. Such apparatus include automatic brewing chambers as well as the means for delivery of a beverage brewing substance to such a chamber and the removal therefrom. One example of such a beverage brewing apparatus is shown in Bunn et al. U.S. Pat. No. 5,134,925, issued Aug. 4, 1992. In the Bunn et al. device, beverage brewing substance is retained and precisely delivered to the brewing chamber for infusion with heated water to produce a brewed beverage. Spent coffee meal is automatically removed from the brewing chamber at the end of each brewing cycle.
A material delivery apparatus is shown in Bunn et al. which includes storage hoppers and delivery augers. Beverage brewing substance, such as ground coffee meal, is stored in the storage hoppers for delivery to the brew chamber upon demand by controlled rotation of the auger. While the material delivery apparatus as shown in Bunn et al. is effective in delivering a precise quantity of beverage brewing substance, it would be advantageous to provide a material delivery apparatus which would agitate the material stored therein. Agitation and vibration is advantageous because it promotes the downward movement of the beverage brewing substance, including fines and powders which may be a part of the substance, towards the output port of the material delivery apparatus.
A device as shown in King U.S. Pat. No. 3,354,810, issued Nov. 28, 1967, shows a material delivery apparatus similar to the device as shown in Bunn et al. with the addition of an agitating device retained in the storage hopper. The device as shown in King employs a gear wheel having multiple teeth in operative association with the auger. Arm members are attached to the gear. Rotation of the auger to dispense material from the hopper causes the gear, and attached arms to rotate. Rotation of the arms through the beverage brewing substance breaks up any lumps which might tend to form therein.
The device in King, however, has a problem in that the device does not prevent "bridging" or "doming" of the brewing substance between the hopper walls. Bridging and/or doming results when material is removed from the center of a volume of material. When the material above the rotating arms, as shown in King, and in contact with the side walls, is removed by the rotating arms a free-standing arch or dome is formed above the rotating arms. Such bridging results when there is sufficient contact and force between the side walls to support the weight of the arch or dome. Therefore, even when rotating arms are employed problems may develop with the flow of material through the storage hoppers. Bridging and doming prevents the even flow of material and requires manual manipulation to knock the material suspended in a bridge into the lower portion of the hopper. The agitator in King does not solve this problem and may, in fact cause the problem. The arms tend to under cut the volume of substance thereby, actually causing the formation of a sufficiently pack volume of substance.
Additionally, it would be advantageous to provide a way to determine when the level of the beverage brewing substance in the hoppers is depleted to a predetermined "low level". In other words, as beverage brewing substance is dispensed from the hoppers it would be advantageous to have some form of signal such as an indicator light, to identify when the predetermined "low-level" exists. Indication of such a low level permits refilling of the hopper before they are emptied. If a hopper is not refilled before it is emptied, the brew cycle in which the last remaining portion of the beverage brewing substance is used may not receive a full portion of substance, or no substance at all, resulting in the beverage brewed during such a cycle being of inferior quality.
The device as shown in Pulvermuller U.S. Pat. No. 4,665,808, issued May 19, 1987, shows a photocell and some form of light-emitting device used to sense the level of substance in a hopper. The device in Pulvermuller positions a photocell at one corner of a storage hopper and a light-emitting device at a diagonally opposite corner. Light is emitted from the light emitting device and received by the photocell. When a volume of brewing substance is in the hopper, the beam path between the light-emitting device and the photocell is obstructed thereby indicating that there is a brewing substance in the hopper. When the level of the substance in the hopper reaches a predetermined low-level, the beam path is not obstructed thereby indicating that the predetermined low level condition exists.
A problem arises with the device in Pulvermuller such that operation of the level sensor depends upon the light-emitting device. This is a problem because if the light-emitting device fails or is somehow obstructed, the sensor will sense a full condition. Further, this arrangement requires the use of multiple components thereby increasing the cost, material handling, repair as well assembly time, materials and effort. It would be highly advantageous to provide a sensing device which only utilizes a sensing device and eliminates the need for a light-emitting device.